Cucurbit[7]uril Enables Multi-Stimuli-Responsive Release from the Self-Assembled Hydrophobic Phase of a Metal Organic Polyhedron

J Am Chem Soc. 2017 Jul 5;139(26):9066-9074. doi: 10.1021/jacs.7b05154. Epub 2017 Jun 23.

Abstract

Mixed self-assembly of ligands 1, 2, 1,6-hexanediamine (HDA), and Pd(NO3)2 afforded Fujita-type metal organic polyhedron MOP1 (diameter ≈ 8.2 nm), which is covalently functionalized with an average of 18 cucurbit[7]uril (CB[7]) units, as evidenced by 1H NMR, diffusion-ordered spectroscopy NMR, and transmission electron microscopy measurements. By virtue of the host-guest properties of CB[7], the inner cavity of MOP can be rendered hydrophobic by using octadecyl HDA (3) as guest during the self-assembly process. The hydrophobic cavity was successfully utilized to trap the hydrophobic dye Nile Red (NR) and the anticancer drug doxorubicin (DOX). The stimuli-responsive release of encapsulated NR or DOX occurs (1) upon addition of a competitive binder (e.g., adamantane ammonium (ADA)) for CB[7], (2) by a dual pH-chemical stimulus involving the protonation state change of adamantane carboxylate at pH 5.8, and (3) by a dual pH-photochemical stimulus involving photoisomerization of trans-6 to cis-6 at pH 5.8. NR is released from NR@MOP2 within HeLa cancer cells. This body of work suggests that the covalent attachment of cucurbit[n]uril to metal organic polyhedra constitutes a promising vehicle for the development of both diagnostic and therapeutic nanoparticles.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bridged-Ring Compounds / chemistry*
  • Hydrophobic and Hydrophilic Interactions
  • Imidazoles / chemistry*
  • Ligands
  • Metal-Organic Frameworks / chemistry*
  • Molecular Structure
  • Photochemistry

Substances

  • Bridged-Ring Compounds
  • Imidazoles
  • Ligands
  • Metal-Organic Frameworks
  • cucurbit(8)uril